Add limits for deployments per pipeline

What does this MR do?

Adds a configurable limit on the number of deployments (jobs with environment specified) allowed in a pipeline, which we will subsequently update to a sensible value (current proposal is 500). It works at the seed stage, so that the deployments are not persisted if the pipeline goes over the limit.

See #24087 (closed)

Screenshots (strongly suggested)

In a project with the following .gitlab-ci.yml, when triggering a pipeline:

deployment_1:
  environment: '1'
  script: [ 'echo 1' ]

deployment_2:
  environment: '2'
  script: [ 'echo 2' ]

we get the following results:

With limit 1	With limit 2 and 0 (disabled)

Migration

plan_limits only has 6 rows (see #database-lab, internal link) by design, so we don't need to worry about timing.

Up

Command:

RAILS_ENV=test bin/rails db:migrate:up VERSION=20201030223933
== 20201030223933 AddCiPipelineDeploymentsToPlanLimits: migrating =============
-- add_column(:plan_limits, :ci_pipeline_deployments, :integer, {:default=>0, :null=>false})
   -> 0.0030s
== 20201030223933 AddCiPipelineDeploymentsToPlanLimits: migrated (0.0031s) ====

git diff:

diff --git a/db/structure.sql b/db/structure.sql
index 8c278442790..110cbeedd76 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -14666,7 +14666,8 @@ CREATE TABLE plan_limits (
     golang_max_file_size bigint DEFAULT 104857600 NOT NULL,
     debian_max_file_size bigint DEFAULT '3221225472'::bigint NOT NULL,
     project_feature_flags integer DEFAULT 200 NOT NULL,
-    ci_max_artifact_size_api_fuzzing integer DEFAULT 0 NOT NULL
+    ci_max_artifact_size_api_fuzzing integer DEFAULT 0 NOT NULL,
+    ci_pipeline_deployments integer DEFAULT 0 NOT NULL
 );
 
 CREATE SEQUENCE plan_limits_id_seq

Down

Command:

$ RAILS_ENV=test bin/rails db:migrate:down VERSION=20201030223933
== 20201030223933 AddCiPipelineDeploymentsToPlanLimits: reverting =============
-- remove_column(:plan_limits, :ci_pipeline_deployments, :integer, {:default=>0, :null=>false})
   -> 0.0026s
== 20201030223933 AddCiPipelineDeploymentsToPlanLimits: reverted (0.0043s) ====

git diff:

diff --git a/db/schema_migrations/20201030223933 b/db/schema_migrations/20201030223933
deleted file mode 100644
index 2fb5f394989..00000000000
--- a/db/schema_migrations/20201030223933
+++ /dev/null
@@ -1 +0,0 @@
-a3aa783f2648a95e3ff8b503ef15b8153759c74ac85b30bf94e39710824e57b0
\ No newline at end of file
diff --git a/db/structure.sql b/db/structure.sql
index 110cbeedd76..8c278442790 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -14666,8 +14666,7 @@ CREATE TABLE plan_limits (
     golang_max_file_size bigint DEFAULT 104857600 NOT NULL,
     debian_max_file_size bigint DEFAULT '3221225472'::bigint NOT NULL,
     project_feature_flags integer DEFAULT 200 NOT NULL,
-    ci_max_artifact_size_api_fuzzing integer DEFAULT 0 NOT NULL,
-    ci_pipeline_deployments integer DEFAULT 0 NOT NULL
+    ci_max_artifact_size_api_fuzzing integer DEFAULT 0 NOT NULL
 );
 
 CREATE SEQUENCE plan_limits_id_seq

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• [-] Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done: Created an issue for them at https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/11931

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team