* remove phase one/two distinction and hdbquery typeclass
* move extensions to default-extensions
* switch to LazyTx which only acquires a connection if needed
* move defns from TH module into Ops module
* remove tojson orphan instance for http exception
* remove orphan instance for dmlp1
* getTopLevelNodes will not throw any exceptions
Fix migration logic to accommodate for non superuser permissions. Closes#567
- [x] Server
By clearing the `hdb_views` schema of existing views and functions instead of dropping and creating it again.
- [x] Bug fix (non-breaking change which fixes an issue)
JWT config now takes an optional jwk_url parameter (which points to published JWK Set). This is useful for providers who rotate their JWK Set.
Optional jwk_url parameter is taken. The published JWK set under that URL should be in standard JWK format (tools.ietf.org/html/rfc7517#section-4.8).
If the response contains an Expires header, the JWK set is automatically refreshed.
### Description
Fixes#495
What component does this PR affect?
- [x] Server
### Solution and Design
Create the extension explicitly mentioning the public schema.
### Type
- [x] Bug fix (non-breaking change which fixes an issue)
The API:
1. HGE has `--jwt-secret` flag or `HASURA_GRAPHQL_JWT_SECRET` env var. The value of which is a JSON.
2. The structure of this JSON is: `{"type": "<standard-JWT-algorithms>", "key": "<the-key>"}`
`type` : Standard JWT algos : `HS256`, `RS256`, `RS512` etc. (see jwt.io).
`key`:
i. Incase of symmetric key, the key as it is.
ii. Incase of asymmetric keys, only the public key, in a PEM encoded string or as a X509 certificate.
3. The claims in the JWT token must contain the following:
i. `x-hasura-default-role` field: default role of that user
ii. `x-hasura-allowed-roles` : A list of allowed roles for the user. The default role is overriden by `x-hasura-role` header.
4. The claims in the JWT token, can have other `x-hasura-*` fields where their values can only be strings.
5. The JWT tokens are sent as `Authorization: Bearer <token>` headers.
---
To test:
1. Generate a shared secret (for HMAC-SHA256) or RSA key pair.
2. Goto https://jwt.io/ , add the keys
3. Edit the claims to have `x-hasura-role` (mandatory) and other `x-hasura-*` fields. Add permissions related to the claims to test permissions.
4. Start HGE with `--jwt-secret` flag or `HASURA_GRAPHQL_JWT_SECRET` env var, which takes a JSON string: `{"type": "HS256", "key": "mylongsharedsecret"}` or `{"type":"RS256", "key": "<PEM-encoded-public-key>"}`
5. Copy the JWT token from jwt.io and use it in the `Authorization: Bearer <token>` header.
---
TODO: Support EC public keys. It is blocked on frasertweedale/hs-jose#61
