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Allow escaping a dollar sign when expanding external labels (#10129) 

* Allow escaping a dollar sign when expanding external labels

There is currently no mechanism to natively escape a dollar sign
in the os.Expand function. As a workaround, this commit modifies
the external label expansion logic to treat a double dollar ($$)
as a mechanism for escaping the dollar character.

Signed-off-by: fpetkovski <filip.petkovsky@gmail.com>
This commit is contained in:
Filip Petkovski 2022-01-17 16:43:55 +01:00 committed by GitHub
parent a56f2856ed
commit 4855a0c067
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
4 changed files with 12 additions and 0 deletions
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3
config/config.go
View File

@ -83,6 +83,9 @@ func Load(s string, expandExternalLabels bool, logger log.Logger) (*Config, erro
for i, v := range cfg.GlobalConfig.ExternalLabels {
newV := os.Expand(v.Value, func(s string) string {
if s == "$" {
return "$"
}
if v := os.Getenv(s); v != "" {
return v
}

6
config/config_test.go
View File

@ -1480,12 +1480,16 @@ func TestExpandExternalLabels(t *testing.T) {
require.Equal(t, labels.Label{Name: "bar", Value: "foo"}, c.GlobalConfig.ExternalLabels[0])
require.Equal(t, labels.Label{Name: "baz", Value: "foo${TEST}bar"}, c.GlobalConfig.ExternalLabels[1])
require.Equal(t, labels.Label{Name: "foo", Value: "${TEST}"}, c.GlobalConfig.ExternalLabels[2])
require.Equal(t, labels.Label{Name: "qux", Value: "foo$${TEST}"}, c.GlobalConfig.ExternalLabels[3])
require.Equal(t, labels.Label{Name: "xyz", Value: "foo$$bar"}, c.GlobalConfig.ExternalLabels[4])
c, err = LoadFile("testdata/external_labels.good.yml", false, true, log.NewNopLogger())
require.NoError(t, err)
require.Equal(t, labels.Label{Name: "bar", Value: "foo"}, c.GlobalConfig.ExternalLabels[0])
require.Equal(t, labels.Label{Name: "baz", Value: "foobar"}, c.GlobalConfig.ExternalLabels[1])
require.Equal(t, labels.Label{Name: "foo", Value: ""}, c.GlobalConfig.ExternalLabels[2])
require.Equal(t, labels.Label{Name: "qux", Value: "foo${TEST}"}, c.GlobalConfig.ExternalLabels[3])
require.Equal(t, labels.Label{Name: "xyz", Value: "foo$bar"}, c.GlobalConfig.ExternalLabels[4])
os.Setenv("TEST", "TestValue")
c, err = LoadFile("testdata/external_labels.good.yml", false, true, log.NewNopLogger())
@ -1493,6 +1497,8 @@ func TestExpandExternalLabels(t *testing.T) {
require.Equal(t, labels.Label{Name: "bar", Value: "foo"}, c.GlobalConfig.ExternalLabels[0])
require.Equal(t, labels.Label{Name: "baz", Value: "fooTestValuebar"}, c.GlobalConfig.ExternalLabels[1])
require.Equal(t, labels.Label{Name: "foo", Value: "TestValue"}, c.GlobalConfig.ExternalLabels[2])
require.Equal(t, labels.Label{Name: "qux", Value: "foo${TEST}"}, c.GlobalConfig.ExternalLabels[3])
require.Equal(t, labels.Label{Name: "xyz", Value: "foo$bar"}, c.GlobalConfig.ExternalLabels[4])
}
func TestEmptyGlobalBlock(t *testing.T) {

2
config/testdata/external_labels.good.yml vendored
View File

@ -3,3 +3,5 @@ global:
bar: foo
foo: ${TEST}
baz: foo${TEST}bar
qux: foo$${TEST}
xyz: foo$$bar

1
docs/feature_flags.md
View File

@ -18,6 +18,7 @@ They may be enabled by default in future versions.
Replace `${var}` or `$var` in the [`external_labels`](configuration/configuration.md#configuration-file)
values according to the values of the current environment variables. References
to undefined variables are replaced by the empty string.
The `$` character can be escaped by using `$$`.
## Remote Write Receiver