Merge pull request #11 from acaire/add_render_command

Add render command

README.md

@@ -72,6 +72,10 @@ steps:
 
 - The time (in seconds) the OIDC token will be valid for before expiry. Must be a non-negative integer. If the flag is omitted or set to 0, the API will choose a default finite lifetime. (default: 0)
 
+### `render-command` (string)
+
+- An installed binary that when specified, will run twice to process the values of `audience` and `service-account` via stdin.  This is intended to be used to render environment variables with an application such as `envsubst`. (default: '')
+
 ## Developing
 
 To run testing, shellchecks and plugin linting use use `bk run` with the [Buildkite CLI](https://github.com/buildkite/cli).

hooks/pre-command

@@ -12,6 +12,16 @@ if [[ -z "${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_SERVICE_ACCOUNT:-}
   exit 1
 fi
 
+if [[ -n "${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_RENDER_COMMAND:-}" ]]; then
+  # Test that the given command exists, otherwise fail
+  command -v "${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_RENDER_COMMAND}" || {
+    echo "🚨 Render command file '${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_RENDER_COMMAND}' not found"
+    exit 1
+  }
+  BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_AUDIENCE="$(echo "${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_AUDIENCE}" | ${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_RENDER_COMMAND})"
+  BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_SERVICE_ACCOUNT="$(echo "${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_SERVICE_ACCOUNT}" | ${BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_RENDER_COMMAND})"
+fi
+
 # Create a temporary directory with both BSD and GNU mktemp
 TMPDIR=$(mktemp -d 2>/dev/null || mktemp -d -t 'buildkiteXXXX')
 

plugin.yml

@@ -13,6 +13,8 @@ configuration:
       type: string
     lifetime:
       type: number
+    render-command:
+      type: string
   required:
     - audience
     - service-account

tests/pre-command.bats

@@ -36,6 +36,16 @@ setup() {
     assert_failure
 }
 
+@test "fails when render command has non-existent binary" {
+    export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_AUDIENCE="//iam.googleapis.com/projects/123456789/locations/global/workloadIdentityPools/buildkite-example-pipeline/providers/buildkite"
+    export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_SERVICE_ACCOUNT="[email protected]"
+    export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_RENDER_COMMAND="this-file-purposely-does-not-exist"
+
+    run "$PWD/hooks/pre-command"
+
+    assert_failure
+}
+
 @test "succeeds when mktemp fails once" {
     export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_AUDIENCE="//iam.googleapis.com/projects/123456789/locations/global/workloadIdentityPools/buildkite-example-pipeline/providers/buildkite"
     export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_SERVICE_ACCOUNT="[email protected]"
@@ -83,3 +93,38 @@ JSON)
     unstub mktemp
     unstub buildkite-agent
 }
+
+@test "exports credentials with render command using envsubst" {
+    export GCP_PROJECT_ID=oidc-project
+    export GCP_PROJECT_NUMBER=123456789
+    export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_AUDIENCE="//iam.googleapis.com/projects/\${GCP_PROJECT_NUMBER}/locations/global/workloadIdentityPools/buildkite-example-pipeline/providers/buildkite"
+    export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_SERVICE_ACCOUNT="buildkite-example-pipeline@\${GCP_PROJECT_ID}.iam.gserviceaccount.com"
+    export BUILDKITE_PLUGIN_GCP_WORKLOAD_IDENTITY_FEDERATION_RENDER_COMMAND="envsubst"
+
+    stub mktemp "-d : echo $BATS_TEST_TMPDIR"
+    stub buildkite-agent "oidc request-token --audience //iam.googleapis.com/projects/123456789/locations/global/workloadIdentityPools/buildkite-example-pipeline/providers/buildkite --lifetime 0 : echo dummy-jwt"
+
+    run "$PWD/hooks/pre-command"
+
+    assert_success
+
+    assert_output --partial "Requesting OIDC token from Buildkite"
+    assert_output --partial "Configuring Google Cloud credentials"
+
+    diff $BATS_TEST_TMPDIR/token.json <(echo dummy-jwt)
+    diff $BATS_TEST_TMPDIR/credentials.json <(cat << JSON
+{
+  "type": "external_account",
+  "audience": "//iam.googleapis.com/projects/123456789/locations/global/workloadIdentityPools/buildkite-example-pipeline/providers/buildkite",
+  "subject_token_type": "urn:ietf:params:oauth:token-type:jwt",
+  "token_url": "https://sts.googleapis.com/v1/token",
+  "service_account_impersonation_url": "https://iamcredentials.googleapis.com/v1/projects/-/serviceAccounts/[email protected]:generateAccessToken",
+  "credential_source": {
+    "file": "$BATS_TEST_TMPDIR/token.json"
+  }
+}
+JSON)
+
+    unstub mktemp
+    unstub buildkite-agent
+}

tests/setup_suite.bash

@@ -0,0 +1,4 @@
+setup_suite() {
+  echo '# Installing envsubst' >&2
+  apk --no-cache add gettext | sed -e 's/^/# /' >&2
+}