diff --git a/docker/conf/lister.yml b/docker/conf/lister.yml
index 5a3c89b..85f7730 100644
--- a/docker/conf/lister.yml
+++ b/docker/conf/lister.yml
@@ -1,31 +1,32 @@
 scheduler:
   cls: remote
   url: http://swh-scheduler:5008/
 
 celery:
   task_broker: amqp://guest:guest@amqp//
   task_queues:
     - swh.lister.bitbucket.tasks.FullBitBucketRelister
     - swh.lister.bitbucket.tasks.IncrementalBitBucketLister
     - swh.lister.bitbucket.tasks.RangeBitBucketLister
     - swh.lister.cgit.tasks.CGitListerTask
     - swh.lister.cran.tasks.CRANListerTask
     - swh.lister.debian.tasks.DebianListerTask
     - swh.lister.gitea.tasks.FullGiteaRelister
     - swh.lister.gitea.tasks.IncrementalGiteaLister
     - swh.lister.gitea.tasks.RangeGiteaLister
     - swh.lister.github.tasks.FullGitHubRelister
     - swh.lister.github.tasks.IncrementalGitHubLister
     - swh.lister.github.tasks.RangeGitHubLister
     - swh.lister.gitlab.tasks.FullGitLabRelister
     - swh.lister.gitlab.tasks.IncrementalGitLabLister
     - swh.lister.gitlab.tasks.RangeGitLabLister
     - swh.lister.gnu.tasks.GNUListerTask
     - swh.lister.npm.tasks.NpmIncrementalListerTask
     - swh.lister.npm.tasks.NpmListerTask
     - swh.lister.launchpad.tasks.IncrementalLaunchpadLister
     - swh.lister.launchpad.tasks.FullLaunchpadLister
     - swh.lister.packagist.tasks.PackagistListerTask
     - swh.lister.phabricator.tasks.FullPhabricatorLister
     - swh.lister.phabricator.tasks.IncrementalPhabricatorLister
+    - swh.lister.opam.tasks.OpamListerTask
     - swh.lister.pypi.tasks.PyPIListerTask
diff --git a/docker/conf/loader-opam.yml b/docker/conf/loader-opam.yml
new file mode 100644
index 0000000..4e94861
--- /dev/null
+++ b/docker/conf/loader-opam.yml
@@ -0,0 +1,19 @@
+storage:
+  cls: pipeline
+  steps:
+    - cls: buffer
+      min_batch_size:
+        content: 10000
+        content_bytes: 104857600
+        directory: 1000
+        revision: 1000
+    - cls: filter
+    - cls: remote
+      url: http://swh-storage:5002/
+
+celery:
+  task_broker: amqp://guest:guest@amqp//
+  task_queues:
+    - swh.loader.package.opam.tasks.LoadOpam
+
+initialize_opam_root: True
diff --git a/docker/docker-compose.yml b/docker/docker-compose.yml
index b342789..11ec8e9 100644
--- a/docker/docker-compose.yml
+++ b/docker/docker-compose.yml
@@ -1,490 +1,510 @@
 version: "2.1"
 
 services:
   amqp:
     image: rabbitmq:3.6-management
     ports:
       - 5072:5672
 
   zookeeper:
     image: wurstmeister/zookeeper
     restart: always
     ports:
       - "5081:2181"
     environment:
         ZOO_LOG4J_PROP: WARN,CONSOLE
 
   kafka:
     image: wurstmeister/kafka
     ports:
       - "5092:5092"
     env_file: ./env/kafka.env
     environment:
       KAFKA_BROKER_ID: 1
       KAFKA_CREATE_TOPICS: swh.journal.objects.content:16:1,
         swh.journal.objects.directory:16:1,
         swh.journal.objects.origin:16:1,
         swh.journal.objects.origin_visit:16:1,
         swh.journal.objects.origin_visit_status:16:1,
         swh.journal.objects.revision:16:1,
         swh.journal.objects.release:16:1,
         swh.journal.objects.skipped_content:16:1,
         swh.journal.objects.snapshot:16:1,
         swh.journal.indexed.origin_intrinsic_metadata:16:1
       KAFKA_ADVERTISED_LISTENERS: PLAINTEXT://kafka:9092,PLAINTEXT_HOST://127.0.0.1:5092
       KAFKA_LISTENERS: PLAINTEXT://:9092,PLAINTEXT_HOST://:5092
       KAFKA_LISTENER_SECURITY_PROTOCOL_MAP: PLAINTEXT:PLAINTEXT,PLAINTEXT_HOST:PLAINTEXT
       KAFKA_INTER_BROKER_LISTENER_NAME: PLAINTEXT
     depends_on:
       - zookeeper
     healthcheck:
       test: "[ `JMX_PORT= kafka-topics.sh --list --zookeeper zookeeper:2181 | wc -l` -ge 6 ]"
       interval: 10s
       timeout: 5s
       retries: 10
 
   cmak:
     # Note: CMAK does not work out of the box, you need to run this first:
     # $ docker-compose exec zookeeper ./bin/zkCli.sh
     #   create /kafka-manager/mutex ""
     #   create /kafka-manager/mutex/locks ""
     #   create /kafka-manager/mutex/leases ""
     # See: https://github.com/yahoo/CMAK/issues/731#issuecomment-643880544
 
     image: hlebalbau/kafka-manager:stable
     environment:
       ZK_HOSTS: "zookeeper:2181"
 
   prometheus:
     image: prom/prometheus
     depends_on:
       - prometheus-statsd-exporter
     command:
       # Needed for the reverse-proxy
       - "--web.external-url=/prometheus"
       - "--config.file=/etc/prometheus/prometheus.yml"
     volumes:
       - "./conf/prometheus.yml:/etc/prometheus/prometheus.yml:ro"
     restart: unless-stopped
 
   prometheus-statsd-exporter:
     image: prom/statsd-exporter
     command:
       - "--statsd.mapping-config=/etc/prometheus/statsd-mapping.yml"
     volumes:
       - "./conf/prometheus-statsd-mapping.yml:/etc/prometheus/statsd-mapping.yml:ro"
     restart: unless-stopped
 
   prometheus-rabbitmq-exporter:
     image: kbudde/rabbitmq-exporter
     restart: unless-stopped
     environment:
       SKIP_QUEUES: "RPC_.*"
       MAX_QUEUES: 5000
       RABBIT_URL: http://amqp:15672
       LOG_LEVEL: warning
 
   grafana:
     image: grafana/grafana
     restart: unless-stopped
     depends_on:
       - prometheus
     environment:
       GF_SERVER_ROOT_URL: http://localhost:5080/grafana
     volumes:
       - "./conf/grafana/provisioning:/etc/grafana/provisioning:ro"
       - "./conf/grafana/dashboards:/var/lib/grafana/dashboards"
 
   mailhog:
     image: mailhog/mailhog
     ports:
       - "1025:1025"
       - "8025:8025"
 
   memcache:
     image: memcached
     restart: unless-stopped
 
   nginx:
     image: nginx
     volumes:
       - "./conf/nginx.conf:/etc/nginx/nginx.conf:ro"
     ports:
       - 5080:5080
 
   # Scheduler
 
   swh-scheduler-db:
     image: postgres:12
     env_file:
       - ./env/common_python.env
       - ./env/scheduler-db.env
 
   swh-scheduler:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/scheduler-db.env
       - ./env/scheduler.env
     environment:
       SWH_CONFIG_FILENAME: /scheduler.yml
       SWH_SCHEDULER_CONFIG_FILE: /scheduler.yml
     entrypoint: /entrypoint.sh
     depends_on:
       - swh-scheduler-db
     ports:
       - 5008:5008
     volumes:
       - "./conf/scheduler.yml:/scheduler.yml:ro"
       - "./services/swh-scheduler/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-scheduler-listener:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/scheduler-db.env
       - ./env/scheduler.env
     environment:
       SWH_CONFIG_FILENAME: /scheduler.yml
       SWH_SCHEDULER_CONFIG_FILE: /scheduler.yml
     entrypoint: /entrypoint.sh
     command: start-listener
     depends_on:
       - swh-scheduler
       - amqp
     volumes:
       - "./conf/scheduler.yml:/scheduler.yml:ro"
       - "./services/swh-scheduler-worker/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-scheduler-runner:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/scheduler-db.env
       - ./env/scheduler.env
     environment:
       SWH_CONFIG_FILENAME: /scheduler.yml
       SWH_SCHEDULER_CONFIG_FILE: /scheduler.yml
     entrypoint: /entrypoint.sh
     command: start-runner --period 10
     depends_on:
       - swh-scheduler
       - amqp
     volumes:
       - "./conf/scheduler.yml:/scheduler.yml:ro"
       - "./services/swh-scheduler-worker/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-scheduler-runner-priority:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/scheduler-db.env
       - ./env/scheduler.env
     environment:
       SWH_CONFIG_FILENAME: /scheduler.yml
       SWH_SCHEDULER_CONFIG_FILE: /scheduler.yml
     entrypoint: /entrypoint.sh
     command: start-runner --period 10 --with-priority --task-type load-git --task-type load-svn --task-type load-hg --task-type load-archive-files
     depends_on:
       - swh-scheduler
       - amqp
     volumes:
       - "./conf/scheduler.yml:/scheduler.yml:ro"
       - "./services/swh-scheduler-worker/entrypoint.sh:/entrypoint.sh:ro"
 
   # Graph storage
 
   swh-storage-db:
     image: postgres:12
     env_file:
       - ./env/storage-db.env
 
   swh-storage:
     image: swh/stack
     build: ./
     ports:
       - 5002:5002
     depends_on:
       - swh-storage-db
       - swh-objstorage
       - kafka
     env_file:
       - ./env/common_python.env
       - ./env/storage.env
     environment:
       SWH_CONFIG_FILENAME: /storage.yml
       STORAGE_BACKEND: postgresql
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/storage.yml:/storage.yml:ro"
       - "./services/swh-storage/entrypoint.sh:/entrypoint.sh:ro"
 
   # Object storage
 
   swh-objstorage:
     build: ./
     image: swh/stack
     ports:
       - 5003:5003
     env_file:
       - ./env/common_python.env
     environment:
       SWH_CONFIG_FILENAME: /objstorage.yml
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/objstorage.yml:/objstorage.yml:ro"
       - "./services/swh-objstorage/entrypoint.sh:/entrypoint.sh:ro"
 
   # Indexer storage
 
   swh-idx-storage-db:
     image: postgres:12
     env_file:
       - ./env/indexers-db.env
 
   swh-idx-storage:
     image: swh/stack
     build: ./
     ports:
       - 5007:5007
     depends_on:
       - swh-idx-storage-db
     env_file:
       - ./env/common_python.env
       - ./env/indexers-db.env
       - ./env/indexers.env
     environment:
       SWH_CONFIG_FILENAME: /indexer_storage.yml
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/indexer_storage.yml:/indexer_storage.yml:ro"
       - "./services/swh-indexer-storage/entrypoint.sh:/entrypoint.sh:ro"
 
   # Web interface
   swh-web-db:
     image: postgres:12
     env_file:
       - ./env/01-web-db.env
 
   swh-web:
     build: ./
     image: swh/stack
     ports:
       - 3000:3000
       - 5004:5004
     depends_on:
       - swh-idx-storage
       - swh-scheduler
       - swh-storage
       - swh-web-db
       - memcache
     env_file:
       - ./env/common_python.env
       - ./env/01-web-db.env
       - ./env/02-web-db.env
     environment:
       VERBOSITY: 3
       DJANGO_SETTINGS_MODULE: swh.web.settings.production
       SWH_CONFIG_FILENAME: /web.yml
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/web.yml:/web.yml:ro"
       - "./services/swh-web/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-deposit-db:
     image: postgres:12
     env_file:
       - ./env/deposit-db.env
 
   swh-deposit:
     image: swh/stack
     build: ./
     ports:
       - 5006:5006
     depends_on:
       - swh-deposit-db
       - swh-scheduler
     env_file:
       - ./env/common_python.env
       - ./env/deposit-db.env
       - ./env/deposit.env
     environment:
       VERBOSITY: 3
       SWH_CONFIG_FILENAME: /deposit.yml
       DJANGO_SETTINGS_MODULE: swh.deposit.settings.production
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/deposit.yml:/deposit.yml:ro"
       - "./services/swh-deposit/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-vault-db:
     image: postgres:12
     env_file:
       - ./env/vault-db.env
 
   swh-vault:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/vault-db.env
       - ./env/vault.env
     environment:
       SWH_CONFIG_FILENAME: /vault.yml
     command: server
     ports:
       - 5005:5005
     depends_on:
       - swh-vault-db
       - swh-objstorage
       - swh-storage
       - swh-scheduler
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/vault.yml:/vault.yml:ro"
       - "./services/swh-vault/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-vault-worker:
     image: swh/stack
     build: ./
     command: worker
     env_file:
       - ./env/common_python.env
       - ./env/workers.env
     environment:
       SWH_CONFIG_FILENAME: /cooker.yml
     depends_on:
       - swh-vault
       - swh-storage
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/vault-worker.yml:/cooker.yml:ro"
       - "./services/swh-vault/entrypoint.sh:/entrypoint.sh:ro"
 
   # Lister Celery workers
 
   swh-lister:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/listers.env
       - ./env/workers.env
     user: swh
     environment:
       SWH_WORKER_INSTANCE: listers
       SWH_CONFIG_FILENAME: /lister.yml
     depends_on:
       - swh-scheduler
       - swh-scheduler-runner
       - amqp
     entrypoint: /entrypoint.sh
     volumes:
       - "./conf/lister.yml:/lister.yml:ro"
       - "./services/swh-listers-worker/entrypoint.sh:/entrypoint.sh:ro"
 
   # Loader + deposit checker Celery workers
 
   swh-loader:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/workers.env
     user: swh
     environment:
       SWH_WORKER_INSTANCE: loader
       SWH_CONFIG_FILENAME: /loader.yml
     entrypoint: /entrypoint.sh
     depends_on:
       - swh-storage
       - swh-scheduler
       - amqp
     volumes:
       - "./conf/loader.yml:/loader.yml:ro"
       - "./services/swh-worker/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-loader-deposit:
     image: swh/stack
     build: ./
     env_file:
       - ./env/common_python.env
       - ./env/workers.env
     user: swh
     environment:
       SWH_WORKER_INSTANCE: loader-deposit
       SWH_CONFIG_FILENAME: /loader-deposit.yml
     entrypoint: /entrypoint.sh
     depends_on:
       - swh-storage
       - swh-scheduler
       - swh-deposit
       - amqp
     volumes:
       - "./conf/loader-deposit.yml:/loader-deposit.yml:ro"
       - "./services/swh-worker/entrypoint.sh:/entrypoint.sh:ro"
 
+  swh-loader-opam:
+    image: swh/stack
+    build: ./
+    env_file:
+      - ./env/common_python.env
+      - ./env/workers.env
+    user: swh
+    environment:
+      SWH_WORKER_INSTANCE: loader-opam
+      SWH_CONFIG_FILENAME: /loader-opam.yml
+    entrypoint: /entrypoint.sh
+    depends_on:
+      - swh-storage
+      - swh-scheduler
+      - swh-deposit
+      - amqp
+    volumes:
+      - "./conf/loader-opam.yml:/loader-opam.yml:ro"
+      - "./services/swh-worker/entrypoint.sh:/entrypoint.sh:ro"
+
   # Indexer Celery workers
 
   swh-indexer:
     image: swh/stack
     build: ./
     user: swh
     env_file:
       - ./env/common_python.env
       - ./env/indexers-db.env
       - ./env/indexers.env
       - ./env/workers.env
     environment:
       SWH_WORKER_INSTANCE: indexer
       SWH_CONFIG_FILENAME: /indexer.yml
       CONCURRENCY: 4
     entrypoint: /entrypoint.sh
     depends_on:
       - swh-scheduler-runner
       - swh-idx-storage
       - swh-storage
       - swh-objstorage
       - amqp
     volumes:
       - "./conf/indexer.yml:/indexer.yml:ro"
       - "./services/swh-indexer-worker/entrypoint.sh:/entrypoint.sh:ro"
 
   # Journal related
 
   swh-indexer-journal-client:
     image: swh/stack
     build: ./
     entrypoint: /entrypoint.sh
     env_file:
       - ./env/common_python.env
     depends_on:
       kafka:
         condition: service_healthy
       swh-storage:
         condition: service_started
       swh-scheduler:
         condition: service_started
 
     volumes:
       - "./conf/indexer_journal_client.yml:/etc/softwareheritage/indexer/journal_client.yml:ro"
       - "./services/swh-indexer-journal-client/entrypoint.sh:/entrypoint.sh:ro"
 
   swh-scheduler-journal-client:
     image: swh/stack
     build: ./
     entrypoint: /entrypoint.sh
     env_file:
       - ./env/common_python.env
     depends_on:
       kafka:
         condition: service_healthy
       swh-scheduler:
         condition: service_started
     volumes:
       - "./conf/scheduler_journal_client.yml:/etc/softwareheritage/scheduler/journal_client.yml:ro"
       - "./services/swh-scheduler-journal-client/entrypoint.sh:/entrypoint.sh:ro"