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MINOR: cfgparse: implement a simple if/elif/else/endif macro block handler
Very often, especially since reg-tests, it would be desirable to be able to conditionally comment out a config block, such as removing an SSL binding when SSL is disabled, or enabling HTX only for certain versions, etc. This patch introduces a very simple nested block management which takes ".if", ".elif", ".else" and ".endif" directives to take or ignore a block. For now the conditions are limited to empty string or "0" for false versus a non-nul integer for true, which already suffices to test environment variables. Still, it needs to be a bit more advanced with defines, versions etc. A set of ".notice", ".warning" and ".alert" statements are provided to emit messages, often in order to provide advice about how to fix certain conditions.
This commit is contained in:
Willy Tarreau
parent
49962b58d0
commit
4b10302fd8
@ -41,8 +41,9 @@ Summary
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2.1. Configuration file format
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2.2. Quoting and escaping
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2.3. Environment variables
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2.4. Time format
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2.5. Examples
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2.4. Conditional blocks
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2.5. Time format
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2.6. Examples
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3. Global parameters
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3.1. Process management and security
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@ -743,7 +744,75 @@ file, or could be inherited by a program (See 3.7. Programs):
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See also "external-check command" for other variables.
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2.4. Time format
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2.4. Conditional blocks
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-----------------------
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It may sometimes be convenient to be able to conditionally enable or disable
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some arbitrary parts of the configuration, for example to enable/disable SSL or
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ciphers, enable or disable some pre-production listeners without modifying the
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configuration, or adjust the configuration's syntax to support two distinct
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versions of HAProxy during a migration.. HAProxy brings a set of nestable
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preprocessor-like directives which allow to integrate or ignore some blocks of
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text. These directives must be placed on their own line and they act on the
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lines that follow them. Two of them support an expression, the other ones only
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switch to an alternate block or end a current level. The 4 following directives
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are defined to form conditional blocks:
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- .if <condition>
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- .elif <condition>
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- .else
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- .endif
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The ".if" directive nests a new level, ".elif" stays at the same level, ".else"
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as well, and ".endif" closes a level. Each ".if" must be terminated by a
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matching ".endif". The ".elif" may only be placed after ".if" or ".elif", and
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there is no limit to the number of ".elif" that may be chained. There may be
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only one ".else" per ".if" and it must always be after the ".if" or the last
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".elif" of a block.
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Comments may be placed on the same line if needed after a '#', they will be
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ignored. The directives are tokenized like other configuration directives, and
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as such it is possible to use environment variables in conditions.
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The conditions are currently limited to:
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- an empty string, always returns "false"
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- the integer zero ('0'), always returns "false"
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- a non-nul integer (e.g. '1'), always returns "true".
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Other patterns are not supported yet but the purpose is to bring a few
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functions to test for certain build options and supported features.
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Three other directives are provided to report some status:
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- .notice "message" : emit this message at level NOTICE
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- .warning "message" : emit this message at level WARNING
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- .alert "message" : emit this message at level ALERT
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Messages emitted at level WARNING may cause the process to fail to start if the
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"strict-mode" is enabled. Messages emitted at level ALERT will always cause a
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fatal error. These can be used to detect some inappropriate conditions and
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provide advice to the user.
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Example:
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.if "${A}"
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.if "${B}"
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.notice "A=1, B=1"
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.elif "${C}"
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.notice "A=1, B=0, C=1"
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.elif "${D}"
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.warning "A=1, B=0, C=0, D=1"
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.else
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.alert "A=1, B=0, C=0, D=0"
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.endif
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.else
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.notice "A=0"
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.endif
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2.5. Time format
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----------------
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Some parameters involve values representing time, such as timeouts. These
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@ -760,7 +829,7 @@ for every keyword. Supported units are :
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- d : days. 1d = 24h = 1440m = 86400s = 86400000ms
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2.5. Examples
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2.6. Examples
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-------------
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# Simple configuration for an HTTP proxy listening on port 80 on all
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@ -10741,7 +10810,7 @@ stick-table type {ip | integer | string [len <length>] | binary [len <length>]}
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was last created, refreshed or matched. The expiration delay is
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defined using the standard time format, similarly as the various
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timeouts. The maximum duration is slightly above 24 days. See
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section 2.4 for more information. If this delay is not specified,
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section 2.5 for more information. If this delay is not specified,
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the session won't automatically expire, but older entries will
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be removed once full. Be sure not to use the "nopurge" parameter
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if not expiration delay is specified.
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@ -10924,7 +10993,7 @@ stick-table type {ip | integer | string [len <length>] | binary [len <length>]}
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# computed over a sliding window of 30 seconds.
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stick-table type ip size 1m expire 5m store gpc0,conn_rate(30s)
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See also : "stick match", "stick on", "stick store-request", section 2.4
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See also : "stick match", "stick on", "stick store-request", section 2.5
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about time format and section 7 about ACLs.
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154
src/cfgparse.c
154
src/cfgparse.c
@ -98,6 +98,23 @@ struct cfg_kw_list cfg_keywords = {
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.list = LIST_HEAD_INIT(cfg_keywords.list)
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};
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/* nested if/elif/else/endif block states */
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enum nested_cond_state {
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NESTED_COND_IF_TAKE, // "if" with a true condition
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NESTED_COND_IF_DROP, // "if" with a false condition
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NESTED_COND_IF_SKIP, // "if" masked by an outer false condition
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NESTED_COND_ELIF_TAKE, // "elif" with a true condition from a false one
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NESTED_COND_ELIF_DROP, // "elif" with a false condition from a false one
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NESTED_COND_ELIF_SKIP, // "elif" masked by an outer false condition or a previously taken if
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NESTED_COND_ELSE_TAKE, // taken "else" after an if false condition
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NESTED_COND_ELSE_DROP, // "else" masked by outer false condition or an if true condition
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};
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/* 100 levels of nested conditions should already be sufficient */
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#define MAXNESTEDCONDS 100
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/*
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* converts <str> to a list of listeners which are dynamically allocated.
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* The format is "{addr|'*'}:port[-end][,{addr|'*'}:port[-end]]*", where :
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@ -1798,6 +1815,8 @@ int readcfgfile(const char *file)
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size_t outlinesize = 0;
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int fatal = 0;
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int missing_lf = -1;
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int nested_cond_lvl = 0;
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enum nested_cond_state nested_conds[MAXNESTEDCONDS];
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if ((thisline = malloc(sizeof(*thisline) * linesize)) == NULL) {
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ha_alert("parsing [%s] : out of memory.\n", file);
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@ -1969,6 +1988,137 @@ next_line:
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if (!**args)
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continue;
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/* check for config macros */
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if (*args[0] == '.') {
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if (strcmp(args[0], ".if") == 0) {
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nested_cond_lvl++;
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if (nested_cond_lvl >= MAXNESTEDCONDS) {
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ha_alert("parsing [%s:%d]: too many nested '.if', max is %d.\n", file, linenum, MAXNESTEDCONDS);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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if (nested_conds[nested_cond_lvl - 1] == NESTED_COND_IF_DROP ||
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nested_conds[nested_cond_lvl - 1] == NESTED_COND_IF_SKIP ||
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nested_conds[nested_cond_lvl - 1] == NESTED_COND_ELIF_DROP ||
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nested_conds[nested_cond_lvl - 1] == NESTED_COND_ELIF_SKIP ||
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nested_conds[nested_cond_lvl - 1] == NESTED_COND_ELSE_DROP) {
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nested_conds[nested_cond_lvl] = NESTED_COND_IF_SKIP;
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} else if (!*args[1] || *args[1] == '0') {
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/* empty = false */
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nested_conds[nested_cond_lvl] = NESTED_COND_IF_DROP;
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} else if (atoi(args[1]) > 0) {
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/* true */
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nested_conds[nested_cond_lvl] = NESTED_COND_IF_TAKE;
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} else {
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ha_alert("parsing [%s:%d]: unparsable conditional expression '%s'.\n", file, linenum, args[1]);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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goto next_line;
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}
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else if (strcmp(args[0], ".elif") == 0) {
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if (!nested_cond_lvl) {
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ha_alert("parsing [%s:%d]: lone '.elif' with no matching '.if'.\n", file, linenum);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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if (nested_conds[nested_cond_lvl] == NESTED_COND_ELSE_TAKE ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELSE_DROP) {
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ha_alert("parsing [%s:%d]: '.elif' after '.else' is not permitted.\n", file, linenum);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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if (nested_conds[nested_cond_lvl] == NESTED_COND_IF_TAKE ||
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nested_conds[nested_cond_lvl] == NESTED_COND_IF_SKIP ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELIF_SKIP) {
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nested_conds[nested_cond_lvl] = NESTED_COND_ELIF_SKIP;
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} else if (!*args[1] || *args[1] == '0') {
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/* empty = false */
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nested_conds[nested_cond_lvl] = NESTED_COND_ELIF_DROP;
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} else if (atoi(args[1]) > 0) {
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/* true */
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nested_conds[nested_cond_lvl] = NESTED_COND_ELIF_TAKE;
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} else {
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ha_alert("parsing [%s:%d]: unparsable conditional expression '%s'.\n", file, linenum, args[1]);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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goto next_line;
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}
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else if (strcmp(args[0], ".else") == 0) {
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if (!nested_cond_lvl) {
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ha_alert("parsing [%s:%d]: lone '.else' with no matching '.if'.\n", file, linenum);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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if (nested_conds[nested_cond_lvl] == NESTED_COND_ELSE_TAKE ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELSE_DROP) {
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ha_alert("parsing [%s:%d]: '.else' after '.else' is not permitted.\n", file, linenum);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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if (nested_conds[nested_cond_lvl] == NESTED_COND_IF_TAKE ||
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nested_conds[nested_cond_lvl] == NESTED_COND_IF_SKIP ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELIF_TAKE ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELIF_SKIP) {
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nested_conds[nested_cond_lvl] = NESTED_COND_ELSE_DROP;
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} else {
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/* otherwise we take the "else" */
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nested_conds[nested_cond_lvl] = NESTED_COND_ELSE_TAKE;
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}
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goto next_line;
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}
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else if (strcmp(args[0], ".endif") == 0) {
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if (!nested_cond_lvl) {
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ha_alert("parsing [%s:%d]: lone '.endif' with no matching '.if'.\n", file, linenum);
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err_code |= ERR_ALERT | ERR_FATAL;
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fatal++;
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break;
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}
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nested_cond_lvl--;
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goto next_line;
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}
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}
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if (nested_cond_lvl &&
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(nested_conds[nested_cond_lvl] == NESTED_COND_IF_DROP ||
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nested_conds[nested_cond_lvl] == NESTED_COND_IF_SKIP ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELIF_DROP ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELIF_SKIP ||
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nested_conds[nested_cond_lvl] == NESTED_COND_ELSE_DROP)) {
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/* The current block is masked out by the conditions */
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goto next_line;
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}
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/* .warning/.error/.notice */
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if (*args[0] == '.') {
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if (strcmp(args[0], ".alert") == 0) {
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ha_alert("parsing [%s:%d]: '%s'.\n", file, linenum, args[1]);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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goto err;
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}
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else if (strcmp(args[0], ".warning") == 0) {
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ha_warning("parsing [%s:%d]: '%s'.\n", file, linenum, args[1]);
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err_code |= ERR_WARN;
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goto next_line;
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}
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else if (strcmp(args[0], ".notice") == 0) {
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ha_notice("parsing [%s:%d]: '%s'.\n", file, linenum, args[1]);
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goto next_line;
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}
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else {
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ha_alert("parsing [%s:%d]: unknown directive '%s'.\n", file, linenum, args[0]);
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err_code |= ERR_ALERT | ERR_FATAL;
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fatal++;
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break;
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}
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}
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/* check for keyword modifiers "no" and "default" */
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if (strcmp(args[0], "no") == 0) {
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char *tmp;
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@ -2046,6 +2196,10 @@ next_line:
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if (cs && cs->post_section_parser)
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err_code |= cs->post_section_parser();
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if (nested_cond_lvl) {
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ha_alert("parsing [%s:%d]: non-terminated '.if' block.\n", file, linenum);
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err_code |= ERR_ALERT | ERR_FATAL | ERR_ABORT;
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}
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err:
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free(cfg_scope);
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cfg_scope = NULL;
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