ci: CircleCI improvements (ethereum#44)

- Use build params to conditionally push builds to Docker Hub
- Use env vars to push both the optimism and optimism-history branches

.circleci/config.yml

@@ -26,33 +26,30 @@ jobs:
       - run:
           command: go run build/ci.go lint
 
-  build-dockerfile:
+  push-geth:
     docker:
       - image: cimg/base:2022.04
-    parameters:
-      image-name:
-        description: Image name
-        type: string
-      image-tag:
-        description: Image tag
-        type: string
-      target:
-        description: Dockerfile target
-        type: string
-        default: ""
-      dockerfile:
-        description: Dockerfile to use
-        type: string
     steps:
-      - checkout
-      - setup_remote_docker:
-          version: 20.10.12
-      - run:
-          name: Build
-          command: |
-            echo "$DOCKER_PASS" | docker login -u "$DOCKER_USERNAME" --password-stdin
-            docker build -t "ethereumoptimism/<<parameters.image-name>>:<<parameters.image-tag>>" -f <<parameters.dockerfile>> <<#parameters.target>>--target <<parameters.target>><</parameters.target>> .
-            docker push "ethereumoptimism/<<parameters.image-name>>:<<parameters.image-tag>>"
+      - when:
+          condition:
+            or:
+              - equal: [ optimism, <<pipeline.git.branch>> ]
+              - equal: [ optimism-history, <<pipeline.git.branch>> ]
+          steps:
+            - checkout
+            - setup_remote_docker:
+                version: 20.10.12
+            - run:
+                name: Build and push
+                command: |
+                  echo "$DOCKER_PASS" | docker login -u "$DOCKER_USERNAME" --password-stdin
+                  docker build -t "ethereumoptimism/reference-optimistic-geth:$CIRCLE_SHA1" -f Dockerfile .
+                  docker tag "ethereumoptimism/reference-optimistic-geth:$CIRCLE_SHA1" "ethereumoptimism/reference-optimistic-geth:$CIRCLE_BRANCH"
+                  docker push "ethereumoptimism/reference-optimistic-geth:$CIRCLE_SHA1"
+                  docker push "ethereumoptimism/reference-optimistic-geth:$CIRCLE_BRANCH"
+      # Below step is required to prevent CircleCI from barfing on a
+      # job with no steps
+      - run: echo 0
 
 workflows:
   main:
@@ -63,21 +60,5 @@ workflows:
           name: Run unit tests for geth
       - lint-geth:
           name: Run linter over geth
-      - build-dockerfile:
-          context:
-            - optimism
-          filters:
-            branches:
-              only:
-                - optimism
-          image-name: reference-optimistic-geth
-          image-tag: latest
-          dockerfile: Dockerfile
-          name: Build reference-optimistic-geth develop
-      - build-dockerfile:
-          context:
-            - optimism
-          image-name: reference-optimistic-geth
-          image-tag: $CIRCLE_SHA1
-          dockerfile: Dockerfile
-          name: Build reference-optimistic-geth per-commit
+      - push-geth:
+          name: Push geth