I'm wondering if a container deployed on cloud run can somehow obtain its own service url or is it impossible?
I'm wanting to know this because I want a cloud run worker that creates google cloud tasks for itself.
If it is possible, how can it be done?
I wrote an article to self call Cloud Run service to prevent Cold Start. The code that I wrote in Go is in my github
The idea is to call the metadata server to find the project number and the region (like this you don't have this hardcoded or in env var), and then you call the namespace API.
If you need help to write it in another language, let me know.
Use namespaces.services.get to retrieve the cloud run service info, some information required for this api
Service name
Cloud Run has provided default environment variable K_SERVICE
Project ID
Region
Access token
Project ID, region and access token can retrieve from metadata server
PROJECT_ID=$(curl "http://metadata.google.internal/computeMetadata/v1/project/project-id" -H "Metadata-Flavor: Google")
REGION=$(curl "http://metadata.google.internal/computeMetadata/v1/instance/region" -H "Metadata-Flavor: Google" | sed "s/.*\///")
TOKEN=$(curl -s "http://metadata.google.internal/computeMetadata/v1/instance/service-accounts/default/token" -H "Metadata-Flavor: Google" | jq -r '.access_token')
Then you can use namespaces.services.get to retrieve the cloud run service info in json, extract url with jq, export environment variable for application use
export PUCLIC_URL=$(curl -s "https://${REGION}-run.googleapis.com/apis/serving.knative.dev/v1/namespaces/${PROJECT_ID}/services/${K_SERVICE}" -H "Authorization: Bearer ${TOKEN}" | jq -r '.status.url')
curl and jq may required to install, for alpine: apk add --no-cache curl jq
Cloud Run service account requires run.services.get permission to call namespaces.services.get
If you know the service name, you can make a GET HTTP request to https://{endpoint}/apis/serving.knative.dev/v1/{name}
Method: namespaces.services.get
For example :
curl -X GET -H "Authorization: Bearer $(gcloud auth print-access-token)" https://us-central1-run.googleapis.com/apis/serving.knative.dev/v1/namespaces/your-project/services/your-service| grep url
"url": "https://cloud-run-xxxxxxxxxx-uc.a.run.app"