Simulating a Multi-Region CockroachDB Cluster on localhost with Docker

Fabio Ghirardello - Sep 15 '20 - - Dev Community

Following are instructions to simulate the deployment of a 9 nodes CockroachDB cluster across 3 regions on localhost using Docker. This is especially useful for testing, training and development work.

The instructions assume you are running Linux or macOS, although it should work on Windows using Cygwin, and have Docker installed.

Below is the high level architecture diagram. Each region will host 3 nodes:

  • region us-west-2 hosts nodes roach-seattle-1|2|3;
  • region us-east-1 hosts nodes roach-newyork-1|2|3
  • region eu-west-1 hosts nodes roach-london-1|2|3.

docker-arch

Setup

Docker resources

It's important to setup Docker with enough resources to run the cluster and the workload you'll be running on top of it. Everyone's environment is different, so this is for reference only.

On my laptop, I have allocated 12 CPUs and 20 GB RAM to Docker. Ensure you have a similar profile; the default 2 CPUs won't be sufficient to run the cluster flawlessly. I use docker with colima:



$ colima list
PROFILE    STATUS     ARCH      CPUS    MEMORY    DISK     RUNTIME    ADDRESS
default    Running    x86_64    12      20GiB     60GiB    docker
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Dockerfile

Create a custom crdb image. We need to add package iproute2, required to simulate the latency between the cluster nodes.

Save locally as file 'Dockerfile'.



FROM ubuntu

RUN apt update \
    && apt install -y wget iproute2 \
    && wget https://binaries.cockroachdb.com/cockroach-latest.linux-amd64.tgz \
    && tar xvf cockroach-latest.linux-amd64.tgz \
    && mv cockroach-*.linux-amd64 cockroach \
    && rm -rf cockroach-latest.linux-amd64.tgz

WORKDIR cockroach

ENTRYPOINT ["/cockroach/cockroach"]
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Build the image with tag name crdb.



docker build -t crdb .
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Verify the image is available to Docker



$ docker image ls
REPOSITORY   TAG       IMAGE ID       CREATED         SIZE
crdb         latest    6e9fa4357b6f   9 minutes ago   406MB
ubuntu       latest    bf3dc08bfed0   3 days ago      76.2MB
haproxy      1.7       41ed9a434c27   2 years ago     83MB
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Good job, the image is ready!

Build the cluster

Create the required networks. We create 1 network for each region, plus 1 network for each inter-regional connection.



# region networks
docker network create --driver=bridge --subnet=172.27.0.0/16 --ip-range=172.27.0.0/24 --gateway=172.27.0.1 us-west-2-net
docker network create --driver=bridge --subnet=172.28.0.0/16 --ip-range=172.28.0.0/24 --gateway=172.28.0.1 us-east-1-net
docker network create --driver=bridge --subnet=172.29.0.0/16 --ip-range=172.29.0.0/24 --gateway=172.29.0.1 eu-west-1-net

# inter-regional networks
docker network create --driver=bridge --subnet=172.30.0.0/16 --ip-range=172.30.0.0/24 --gateway=172.30.0.1 uswest-useast-net
docker network create --driver=bridge --subnet=172.31.0.0/16 --ip-range=172.31.0.0/24 --gateway=172.31.0.1 useast-euwest-net
docker network create --driver=bridge --subnet=172.32.0.0/16 --ip-range=172.32.0.0/24 --gateway=172.32.0.1 uswest-euwest-net
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Each node is associated to its own region network, which will attach to the docker instance eth0 NIC. We also specify the node IP address with the --ip flag and the IP addresses of all nodes in its region using the --add-host flag. This will create an entry in the docker instance /etc/hosts file, which has precedence over DNS lookups. It will come clear later why this is important.

Create the haproxy.cfg files for the HAProxy in each region.



# us-east-1
mkdir -p data/us-east-1
cat - >data/us-east-1/haproxy.cfg <<EOF

global
  maxconn 4096

defaults
    mode                tcp
    # Timeout values should be configured for your specific use.
    # See: https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#4-timeout%20connect
    timeout connect     10s
    timeout client      10m
    timeout server      10m
    # TCP keep-alive on client side. Server already enables them.
    option              clitcpka

listen psql
    bind :26257
    mode tcp
    balance roundrobin
    option httpchk GET /health?ready=1
    server cockroach1 roach-newyork-1:26257 check port 8080
    server cockroach2 roach-newyork-3:26257 check port 8080
    server cockroach3 roach-newyork-2:26257 check port 8080

EOF

# us-west-2
mkdir data/us-west-2
cat - >data/us-west-2/haproxy.cfg <<EOF

global
  maxconn 4096

defaults
    mode                tcp
    # Timeout values should be configured for your specific use.
    # See: https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#4-timeout%20connect
    timeout connect     10s
    timeout client      10m
    timeout server      10m
    # TCP keep-alive on client side. Server already enables them.
    option              clitcpka

listen psql
    bind :26257
    mode tcp
    balance roundrobin
    option httpchk GET /health?ready=1
    server cockroach4 roach-seattle-1:26257 check port 8080
    server cockroach5 roach-seattle-2:26257 check port 8080
    server cockroach6 roach-seattle-3:26257 check port 8080

EOF

# eu-west-1
mkdir data/eu-west-1
cat - >data/eu-west-1/haproxy.cfg <<EOF

global
  maxconn 4096

defaults
    mode                tcp
    # Timeout values should be configured for your specific use.
    # See: https://cbonte.github.io/haproxy-dconv/1.8/configuration.html#4-timeout%20connect
    timeout connect     10s
    timeout client      10m
    timeout server      10m
    # TCP keep-alive on client side. Server already enables them.
    option              clitcpka

listen psql
    bind :26257
    mode tcp
    balance roundrobin
    option httpchk GET /health?ready=1
    server cockroach7 roach-london-1:26257 check port 8080
    server cockroach8 roach-london-2:26257 check port 8080
    server cockroach9 roach-london-3:26257 check port 8080
EOF
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Create the docker containers



# Seattle
docker run -d --name=roach-seattle-1 --hostname=roach-seattle-1 --ip=172.27.0.11 --cap-add NET_ADMIN --net=us-west-2-net --add-host=roach-seattle-1:172.27.0.11 --add-host=roach-seattle-2:172.27.0.12 --add-host=roach-seattle-3:172.27.0.13 -p 8080:8080 -v "roach-seattle-1-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=us-west-2,zone=a
docker run -d --name=roach-seattle-2 --hostname=roach-seattle-2 --ip=172.27.0.12 --cap-add NET_ADMIN --net=us-west-2-net --add-host=roach-seattle-1:172.27.0.11 --add-host=roach-seattle-2:172.27.0.12 --add-host=roach-seattle-3:172.27.0.13 -p 8081:8080 -v "roach-seattle-2-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=us-west-2,zone=b
docker run -d --name=roach-seattle-3 --hostname=roach-seattle-3 --ip=172.27.0.13 --cap-add NET_ADMIN --net=us-west-2-net --add-host=roach-seattle-1:172.27.0.11 --add-host=roach-seattle-2:172.27.0.12 --add-host=roach-seattle-3:172.27.0.13 -p 8082:8080 -v "roach-seattle-3-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=us-west-2,zone=c
# Seattle HAProxy
docker run -d --name haproxy-seattle --ip=172.27.0.10 -p 26257:26257 --net=us-west-2-net -v `pwd`/data/us-west-2/:/usr/local/etc/haproxy:ro haproxy:1.7  

# New York
docker run -d --name=roach-newyork-1 --hostname=roach-newyork-1 --ip=172.28.0.11 --cap-add NET_ADMIN --net=us-east-1-net --add-host=roach-newyork-1:172.28.0.11 --add-host=roach-newyork-2:172.28.0.12 --add-host=roach-newyork-3:172.28.0.13 -p 8180:8080 -v "roach-newyork-1-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=us-east-1,zone=a
docker run -d --name=roach-newyork-2 --hostname=roach-newyork-2 --ip=172.28.0.12 --cap-add NET_ADMIN --net=us-east-1-net --add-host=roach-newyork-1:172.28.0.11 --add-host=roach-newyork-2:172.28.0.12 --add-host=roach-newyork-3:172.28.0.13 -p 8181:8080 -v "roach-newyork-2-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=us-east-1,zone=b
docker run -d --name=roach-newyork-3 --hostname=roach-newyork-3 --ip=172.28.0.13 --cap-add NET_ADMIN --net=us-east-1-net --add-host=roach-newyork-1:172.28.0.11 --add-host=roach-newyork-2:172.28.0.12 --add-host=roach-newyork-3:172.28.0.13 -p 8182:8080 -v "roach-newyork-3-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=us-east-1,zone=c
# New York HAProxy
docker run -d --name haproxy-newyork --ip=172.28.0.10 -p 26258:26257 --net=us-east-1-net -v `pwd`/data/us-east-1/:/usr/local/etc/haproxy:ro haproxy:1.7  

# London
docker run -d --name=roach-london-1 --hostname=roach-london-1 --ip=172.29.0.11 --cap-add NET_ADMIN --net=eu-west-1-net --add-host=roach-london-1:172.29.0.11 --add-host=roach-london-2:172.29.0.12 --add-host=roach-london-3:172.29.0.13 -p 8280:8080 -v "roach-london-1-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=eu-west-1,zone=a
docker run -d --name=roach-london-2 --hostname=roach-london-2 --ip=172.29.0.12 --cap-add NET_ADMIN --net=eu-west-1-net --add-host=roach-london-1:172.29.0.11 --add-host=roach-london-2:172.29.0.12 --add-host=roach-london-3:172.29.0.13 -p 8281:8080 -v "roach-london-2-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=eu-west-1,zone=b
docker run -d --name=roach-london-3 --hostname=roach-london-3 --ip=172.29.0.13 --cap-add NET_ADMIN --net=eu-west-1-net --add-host=roach-london-1:172.29.0.11 --add-host=roach-london-2:172.29.0.12 --add-host=roach-london-3:172.29.0.13 -p 8282:8080 -v "roach-london-3-data:/cockroach/cockroach-data" crdb start --insecure --join=roach-seattle-1,roach-newyork-1,roach-london-1 --locality=region=eu-west-1,zone=c
# London HAProxy
docker run -d --name haproxy-london --ip=172.29.0.10 -p 26259:26257 --net=eu-west-1-net -v `pwd`/data/eu-west-1/:/usr/local/etc/haproxy:ro haproxy:1.7
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Initialize the cluster



docker exec -it roach-newyork-1 ./cockroach init --insecure
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We then attach each node to the inter-regional networks. These networks will attach to new NICs, eth1 and eth2. We then use tc qdisc to add an arbitrary latency to each new NIC.

Connectivity between nodes in the same region will go through the region network, over eth0, and connectivity among nodes in different regions via the inter-regional network, over eth1 and eth2.

Note: with the connection to the inter-regional networks, the docker instance internal DNS gets sometimes scrambled up: issuing, say, nslookup roach-seattle-1 from host roach-seattle-2 will resolve to either an IP address from the in-region network or from the inter-regional networks. If the hostname does not resolve to the in-region network IP, traffic will go through eth1 or eth2 which has the latency applied, causing in-region connectivity to look very slow. To resolve such a problem we use static IP addresses added to each node's /etc/hosts file. This makes sure that in-region hostnames resolve to the region IP addresses, forcing the connection to go over eth0 instead of eth1 or eth2.



# Seattle
for j in 1 2 3
do
    docker network connect uswest-useast-net roach-seattle-$j
    docker network connect uswest-euwest-net roach-seattle-$j
    docker exec roach-seattle-$j tc qdisc add dev eth1 root netem delay 30ms
    docker exec roach-seattle-$j tc qdisc add dev eth2 root netem delay 90ms
done

# New York
for j in 1 2 3
do
    docker network connect uswest-useast-net roach-newyork-$j
    docker network connect useast-euwest-net roach-newyork-$j
    docker exec roach-newyork-$j tc qdisc add dev eth1 root netem delay 32ms
    docker exec roach-newyork-$j tc qdisc add dev eth2 root netem delay 60ms
done

# London
for j in 1 2 3
do
    docker network connect useast-euwest-net roach-london-$j
    docker network connect uswest-euwest-net roach-london-$j
    docker exec roach-london-$j tc qdisc add dev eth1 root netem delay 62ms
    docker exec roach-london-$j tc qdisc add dev eth2 root netem delay 88ms
done
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Cluster configuration

You will require an Enterprise license to unlock some of the features described below, like the Map view. You can request a Trial license or, alternatively, just skip the license registration step - the deployment will still succeed.

Open a SQL shell. You can download the cockroachdb binary which includes a built in SQL client or, thanks to CockroachDB's compliance with the PostgreSQL wire protocol, you can use the psql client. 



# ----------------------------
# ports mapping:
# 26257: haproxy-seattle
# 26258: haproxy-newyork
# 26259: haproxy-london
# ----------------------------

# use cockroach sql, defaults to localhost:26257
cockroach sql --insecure

# or use the --url param for another host:
cockroach sql --url "postgresql://localhost:26258/defaultdb?sslmode=disable"

# or use psql
psql -h localhost -p 26257 -U root defaultdb
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Run below SQL statements:



-- let the map know the location of the regions
UPSERT into system.locations VALUES
        ('region', 'us-east-1', 37.478397, -76.453077),
        ('region', 'us-west-2', 43.804133, -120.554201),
        ('region', 'eu-west-1', 53.142367, -7.692054);

SET CLUSTER SETTING cluster.organization = "Your Company Name";
-- skip below if you don't have a Trial or Enterprise license
SET CLUSTER SETTING enterprise.license = "xxxx-yyyy-zzzz";
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At this point you should be able to view the CockroachDB Admin UI at http://localhost:8080. Check the map and the latency table:

crdb-map

crdb-latency

Congratulations, you are now ready to start your dev work on a simulated multi-region deployment!

References

CockroachDB Docs

CockroachDB docker image

Docker Network Overview

HAProxy Docs

HAProxy docker image

Clean up

Stop and remove containers, delete the data volumes, delete the network bridges



for i in seattle newyork london
do
    for j in 1 2 3
    do
        docker stop roach-$i-$j
        docker rm roach-$i-$j
        docker volume rm roach-$i-$j-data
    done
done
docker network rm us-east-1-net us-west-2-net eu-west-1-net uswest-useast-net useast-euwest-net uswest-euwest-net
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