Curl requests to minikube time out, dont understand why

I'm working thru Chapter 5 of Cloud Native Patterns (Cornelia Davis, Manning Press, (c) 2019). I'm trying to access a minikube service thru a curl command, but consistently time out.

I'm running on a Windows 10 Home computer. It has Docker (with virtual box), Minikube, kubectl, MySql 8, and OpenJdk 1.8. I'm using the Bash terminal (MINGW64) provided by GIT.

Per instructions, I'm using the author's provided apps (connection, post, connection+post) and compiled them with Maven. I then uploaded them to my Docker Hub account, so that Docker can use them. Then I started mysql-svc thru kubectl, just as the tutorial tells me to.

After starting mysql, I used a minikube service mysql-svc --format ... command to get the IP:Port and installed it into the YAML file for each of the connection service and post service. I started the two services, and they -- momentarily -- were up and running.

Here is my cluster status:

$ kubectl get all
NAME                              READY   STATUS             RESTARTS   AGE
pod/connections-56bcf7896-h4tz7   0/1     CrashLoopBackOff   8          26m
pod/mysql-7dbfd4dbc4-2jsjt        1/1     Running            0          24h
pod/posts-5d7f46b546-crfmj        1/1     Running            1          102s

NAME                      TYPE        CLUSTER-IP      EXTERNAL-IP   PORT(S)          AGE
service/connections-svc   NodePort    10.104.27.91    <none>        80:31286/TCP     26m
service/kubernetes        ClusterIP   10.96.0.1       <none>        443/TCP          2d12h
service/mysql-svc         NodePort    10.107.19.70    <none>        3306:31067/TCP   24h
service/posts-svc         NodePort    10.97.232.158   <none>        80:31651/TCP     103s

NAME                          READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/connections   0/1     1            0           26m
deployment.apps/mysql         1/1     1            1           24h
deployment.apps/posts         1/1     1            1           103s

NAME                                    DESIRED   CURRENT   READY   AGE
replicaset.apps/connections-56bcf7896   1         1         0       26m
replicaset.apps/mysql-7dbfd4dbc4        1         1         1       24h
replicaset.apps/posts-5d7f46b546        1         1         1       103s

OK, the posts service is up. So ask it for something:

$ curl $(minikube service --url posts-svc)/posts
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
  0     0    0     0    0     0      0      0 --:--:--  0:00:02 --:--:--     0
curl: (7) Failed to connect to 192.168.99.101 port 31651: Connection refused

I don't know why it is refusing, and can someone explain? Or at least provide an approach for why connections are refused, even though I've got the IP:Port correct.

A perhaps related problem is that the services keep crashing. Not even four minutes later and the posts-svc has crashed multiple times:

$ kubectl get all
NAME                              READY   STATUS             RESTARTS   AGE
pod/connections-56bcf7896-h4tz7   0/1     CrashLoopBackOff   9          28m
pod/mysql-7dbfd4dbc4-2jsjt        1/1     Running            0          24h
pod/posts-5d7f46b546-crfmj        0/1     CrashLoopBackOff   3          3m53s
[SNIP]

How might I get more stability here?

Thanks,

Jerome.

UPDATE 8/11/2020:

After looking through logs I changed these things:

• The minikube startup file mysql-deployment.yaml now explicitly uses the password, such as

  containers:
  - name: mysql
    image: mysql:5.7.22
    env:
      - name: MYSQL_ROOT_PASSWORD
        value: "the_actual_password"
  

• I added a dialect to the application.properties file. Now the example's h2 test files don't like that dialect, so I recompiled skipping the tests. I can add an h2 dialect to the tests later on.

    spring.jpa.properties.hibernate.dialect = org.hibernate.dialect.MySQL57Dialect
  

Now all I get is that the root user can't login:

    java.sql.SQLException: Access denied for user 'root'@'172.17.0.1' (using password: YES)

From the mysql CLI, I can login as root and access the 'cookbook' database that this code uses. I checked that root has all grants, etc. It just doesn't work.

Any more clues?

Jerome.

UPDATE ON 8/12/2020:

I have good results now. Here is what is different between my complaint and now.

The tutorial had me download a MySQL version thru Docker. However, I also have a PC version of MySQL on my computer. I thought that the Docker / Minikube servers would somehow use the downloaded MySQL to connect to my desktop MySQL. So I modified the download command, and the .yaml file used to do the Minikube startup of mysql-svc, to duplicate the version #, password, and possibly other aspects of using MySQL. The net effect is that the program and mysql don't like each other, so the services keep restarting.

The correct way to approach Minikube is that all of the needed software is downloaded into the container, and it doesn't touch what is already there. I read that but didn't obviously understand it. Now I have burned fingers, and see that the container has all the programs I need.

So I restored all configuration to what the GIT repository started with, and I replaced the mysql I originally installed (version 8.+, to match my desktop) with the one the tutorial asked for (5.7.22).

After recompiling, and then pushing the changes to my Docker Hub account, everything works just as the tutorial promised. Note that this book has a number of typos in commands, notably missing the clause '--url' in "minikube service..." commands on p.121. Be wary.

My earlier accounting said that I created my files "per instructions", but I was blind to the changes that I actually made.

Jerome.

Sorry, Yet Another UPDATE on 08/13/2020:

I said I eventually used the .yaml configuration files exactly as provided. I actually made two changes.

1. The files had apiVersion: apps/v1beta . This must become apps/v1 or
   other things don't work.

2. The files sought their Docker Hub images as cdavisafc/*, such as cdavisafc/cloudnative-statelessness-posts. Because I put the images into my own Docker Hub account, my images are named logicaltiger/cloudnative-statelessness-posts, etc.

The tutorial says good things, but you'll learn plenty about docker and minikube just thru getting the provided code to actually deploy OK.

Jerome.

When starting minikube, try adjusting RAM and memory (--cpus 4 --memory 8192, given your computer have those resources available).
It seems like minikube is not having enough resources to perform it's own tasks correctly.

Minikube is fragile when it comes to lack of available resources and if resources are low, you might need to stop/start multiple times until it boots up correctly.

You might also want to run some diagnostics to get more information as to why your pods are crashing.

kubectl describe pod connections-56bcf7896-h4tz7
kubectl describe pod posts-5d7f46b546-crfmj
kubectl describe deployment connections
kubectl describe deployment posts
kubectl logs connections-56bcf7896-h4tz7
kubectl logs posts-5d7f46b546-crfmj

You should get some indication from those commands as to why your pods are failing.