[vtadmin-api] Add /api/schemas endpoint to vtadmin-api

[doeg]

Signed-off-by: Sara Bee 855595+doeg@users.noreply.github.com

Description

A simplified version of our Slack-internal /api/schemas endpoint. Notably:

• This does not provide a mechanism to filter by anything other than cluster ID
• This does not implement any caching

"Don't forget" to expand the api_test.go diff 😭

@ajm188 thanks as always for weathering my incessant whining questions!

Queries against local Vitess

curl "http://localhost:14200/api/schemas" | jq .

{
  "result": {
    "schemas": [
      {
        "cluster": {
          "id": "id1",
          "name": "cluster1"
        },
        "keyspace": "commerce",
        "table_definitions": [
          {
            "name": "customer_seq",
            "schema": "CREATE TABLE `customer_seq` (\n  `id` int(11) NOT NULL,\n  `next_id` bigint(20) DEFAULT NULL,\n  `cache` bigint(20) DEFAULT NULL,\n  PRIMARY KEY (`id`)\n) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='vitess_sequence'",
            "columns": [
              "id",
              "next_id",
              "cache"
            ],
            "primary_key_columns": [
              "id"
            ],
            "type": "BASE TABLE",
            "data_length": 16384,
            "row_count": 1,
            "fields": [
              {
                "name": "id",
                "type": 263,
                "table": "customer_seq",
                "org_table": "customer_seq",
                "database": "vt_commerce",
                "org_name": "id",
                "column_length": 11,
                "charset": 63,
                "flags": 53251
              },
              {
                "name": "next_id",
                "type": 265,
                "table": "customer_seq",
                "org_table": "customer_seq",
                "database": "vt_commerce",
                "org_name": "next_id",
                "column_length": 20,
                "charset": 63,
                "flags": 32768
              },
              {
                "name": "cache",
                "type": 265,
                "table": "customer_seq",
                "org_table": "customer_seq",
                "database": "vt_commerce",
                "org_name": "cache",
                "column_length": 20,
                "charset": 63,
                "flags": 32768
              }
            ]
          },
          {
            "name": "order_seq",
            "schema": "CREATE TABLE `order_seq` (\n  `id` int(11) NOT NULL,\n  `next_id` bigint(20) DEFAULT NULL,\n  `cache` bigint(20) DEFAULT NULL,\n  PRIMARY KEY (`id`)\n) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='vitess_sequence'",
            "columns": [
              "id",
              "next_id",
              "cache"
            ],
            "primary_key_columns": [
              "id"
            ],
            "type": "BASE TABLE",
            "data_length": 16384,
            "row_count": 1,
            "fields": [
              {
                "name": "id",
                "type": 263,
                "table": "order_seq",
                "org_table": "order_seq",
                "database": "vt_commerce",
                "org_name": "id",
                "column_length": 11,
                "charset": 63,
                "flags": 53251
              },
              {
                "name": "next_id",
                "type": 265,
                "table": "order_seq",
                "org_table": "order_seq",
                "database": "vt_commerce",
                "org_name": "next_id",
                "column_length": 20,
                "charset": 63,
                "flags": 32768
              },
              {
                "name": "cache",
                "type": 265,
                "table": "order_seq",
                "org_table": "order_seq",
                "database": "vt_commerce",
                "org_name": "cache",
                "column_length": 20,
                "charset": 63,
                "flags": 32768
              }
            ]
          },
          {
            "name": "product",
            "schema": "CREATE TABLE `product` (\n  `sku` varbinary(128) NOT NULL,\n  `description` varbinary(128) DEFAULT NULL,\n  `price` bigint(20) DEFAULT NULL,\n  PRIMARY KEY (`sku`)\n) ENGINE=InnoDB DEFAULT CHARSET=utf8",
            "columns": [
              "sku",
              "description",
              "price"
            ],
            "primary_key_columns": [
              "sku"
            ],
            "type": "BASE TABLE",
            "data_length": 16384,
            "fields": [
              {
                "name": "sku",
                "type": 10262,
                "table": "product",
                "org_table": "product",
                "database": "vt_commerce",
                "org_name": "sku",
                "column_length": 128,
                "charset": 63,
                "flags": 20611
              },
              {
                "name": "description",
                "type": 10262,
                "table": "product",
                "org_table": "product",
                "database": "vt_commerce",
                "org_name": "description",
                "column_length": 128,
                "charset": 63,
                "flags": 128
              },
              {
                "name": "price",
                "type": 265,
                "table": "product",
                "org_table": "product",
                "database": "vt_commerce",
                "org_name": "price",
                "column_length": 20,
                "charset": 63,
                "flags": 32768
              }
            ]
          }
        ]
      }
    ]
  },
  "ok": true
}

curl "http://localhost:14200/api/schemas?cluster=nope" | jq .

{
  "result": {},
  "ok": true
}

Related Issue(s)

• [vtctld] Migrate GetSchema #7346

Checklist

• Should this PR be backported?
• Tests were added or are not required
• Documentation was added or is not required

Deployment Notes

N/A

Impacted Areas in Vitess

Components that this PR will affect:

• Query Serving
• VReplication
• Cluster Management
• Build/CI
• VTAdmin

[ajm188]

lg2m!

[ajm188]

TIOLI: I know we talked a bit about this file potentially growing very large as the API surface area grows, and these methods don't actually depend on api for anything, so if you wanted to you could make these top-level private functions in another file, but also this is fine as-is.

[doeg]

I'll leave it for now. I agree with you on one file offering better readability. Even though these methods don't use api directly, the colocation seems good. One day I'll get used to the verbosity.

[ajm188]

Ugh, I am sorry lol. These are great tests though!