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yccheok / cheatsheet

Cheastsheet for programmer

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Command to keep the container running (For easy debugging)

CMD ["tail", "-f", "/dev/null"]

How to restore SQL dump file from production?

1) Place pg_dump-20240129_000002.sql in postgres folder.

2) Change postgres/Dockerfile to

    FROM postgres:13.3

    RUN mkdir /postgres_logs
    RUN chown postgres:postgres /postgres_logs

    ENV POSTGRES_DB wenote_cloud_storage

    ADD postgres.sql /docker-entrypoint-initdb.d/


    COPY . /app
    WORKDIR /app

3) docker-compose exec postgres bash

4) psql -h localhost -U postgres

5) drop DATABASE wenote_cloud_storage;

6) create DATABASE wenote_cloud_storage;

7) exit

8) psql -U postgres wenote_cloud_storage < pg_dump-20240129_000002.sql

How to capture images for the onboarding screen in iOS?

  1. Use an iPhone SE (3rd generation) with iOS 16.2.
  2. Set the font size to Large.
  3. Capture a screenshot in the simulator with the size of 750x1334 pixels.
  4. Use Gimp to edit the screenshot down to a region with the size of 750x1024 pixels.

Replicate a bug seen when installing an app via App Bundle from the Google Play store?

// Generate APKs.
bundletool build-apks --bundle=~/Desktop/com.yocto.wenote-536-5.36-release.aab --output=~/Desktop/output.apks --ks=~/yocto/my-release-key.jks --ks-key-alias=yocto

// Install APK to connected device. Connected device can be an emulator.
bundletool install-apks --apks=~/Desktop/output.apks

Create custom Java runtime image

jlink --no-header-files --no-man-pages --compress=2 --strip-debug --module-path "C:\Program Files\Zulu\zulu-17\jmods" --add-modules java.base,java.datatransfer,java.desktop,java.logging,java.naming,java.prefs,java.rmi,java.security.sasl,java.sql,java.xml,javafx.base,javafx.controls,javafx.graphics,javafx.media,javafx.swing,javafx.web,jdk.jsobject,jdk.unsupported,jdk.crypto.ec --output jre

Find all dependencies

C:\Users\yccheok\Desktop\jstock>jdeps --ignore-missing-deps --list-deps jstock.jar lib\*.jar
Warning: split package: javax.xml jrt:/java.xml lib\stax-api-1.0.1.jar lib\xml-apis.jar
Warning: split package: javax.xml.datatype jrt:/java.xml lib\xml-apis.jar
Warning: split package: javax.xml.namespace jrt:/java.xml lib\stax-api-1.0.1.jar lib\xml-apis.jar
Warning: split package: javax.xml.parsers jrt:/java.xml lib\xml-apis.jar
Warning: split package: javax.xml.stream jrt:/java.xml lib\stax-api-1.0.1.jar
Warning: split package: javax.xml.stream.events jrt:/java.xml lib\stax-api-1.0.1.jar
Warning: split package: javax.xml.stream.util jrt:/java.xml lib\stax-api-1.0.1.jar
Warning: split package: javax.xml.transform jrt:/java.xml lib\xml-apis.jar
Warning: split package: javax.xml.transform.dom jrt:/java.xml lib\xml-apis.jar
Warning: split package: javax.xml.transform.sax jrt:/java.xml lib\xml-apis.jar
Warning: split package: javax.xml.transform.stream jrt:/java.xml lib\xml-apis.jar
Warning: split package: javax.xml.validation jrt:/java.xml lib\xml-apis.jar
Warning: split package: javax.xml.xpath jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.w3c.dom jrt:/java.xml lib\xml-apis.jar lib\xom-1.1.jar
Warning: split package: org.w3c.dom.bootstrap jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.w3c.dom.css jrt:/jdk.xml.dom lib\xml-apis.jar
Warning: split package: org.w3c.dom.events jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.w3c.dom.html jrt:/jdk.xml.dom lib\xercesImpl.jar lib\xml-apis.jar
Warning: split package: org.w3c.dom.ls jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.w3c.dom.ranges jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.w3c.dom.stylesheets jrt:/jdk.xml.dom lib\xml-apis.jar
Warning: split package: org.w3c.dom.traversal jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.w3c.dom.views jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.w3c.dom.xpath jrt:/jdk.xml.dom lib\xml-apis.jar
Warning: split package: org.xml.sax jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.xml.sax.ext jrt:/java.xml lib\xml-apis.jar
Warning: split package: org.xml.sax.helpers jrt:/java.xml lib\xml-apis.jar
   java.base
   java.datatransfer
   java.desktop/sun.awt.geom
   java.logging
   java.naming
   java.prefs
   java.rmi
   java.security.sasl
   java.sql
   java.xml/com.sun.org.apache.xerces.internal.parsers
   java.xml/com.sun.org.apache.xerces.internal.util
   java.xml/com.sun.org.apache.xerces.internal.xni.parser
   javafx.base/com.sun.javafx.collections
   javafx.base/com.sun.javafx.event
   javafx.base/com.sun.javafx.runtime
   javafx.controls/com.sun.javafx.scene.control
   javafx.controls/com.sun.javafx.scene.control.behavior
   javafx.graphics/com.sun.javafx.css
   javafx.graphics/com.sun.javafx.scene.traversal
   javafx.media
   javafx.swing
   javafx.web/com.sun.javafx.webkit
   javafx.web/com.sun.webkit
   jdk.jsobject
   jdk.unsupported

An additional dependency jdk.crypto.ec is required, due to runtime error when we are trying to perform news fetching - https://stackoverflow.com/questions/54770538/received-fatal-alert-handshake-failure-in-jlinked-jre/54785281#54785281

How to execute JStock

C:\Users\yccheok\Desktop\jstock>jre\bin\java.exe -Dsun.java2d.dpiaware=false -Xms64m  -Xmx512m --add-opens java.base/java.util=ALL-UNNAMED --add-opens java.base/java.lang.reflect=ALL-UNNAMED --add-opens java.base/java.text=ALL-UNNAMED --add-opens java.desktop/java.awt.font=ALL-UNNAMED --add-opens java.desktop/java.awt=ALL-UNNAMED -jar jstock.jar

Rounded corner ripple effect

<?xml version="1.0" encoding="utf-8"?>
<ripple android:color="?android:colorControlHighlight"
    xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:id="@android:id/mask">
        <shape android:shape="rectangle">
            <corners android:topLeftRadius="16dp" android:topRightRadius="16dp"
                android:bottomLeftRadius="0dp" android:bottomRightRadius="0dp" />
            <solid android:color="@android:color/white" />
        </shape>
    </item>

    <item>
        <shape android:shape="rectangle">
            <corners android:topLeftRadius="16dp" android:topRightRadius="16dp"
                android:bottomLeftRadius="0dp" android:bottomRightRadius="0dp" />
            <solid android:color="@color/white_90" />
        </shape>
    </item>
</ripple>

How to have a fullscreen Android app

  1. Apply app:elevation="0dp" in AppBarLayout.
  2. Apply android:background="@android:color/transparent" in AppBarLayout and Toolbar.
  3. Apply <style name="Theme.MyApplication.AppBarOverlay" parent="ThemeOverlay.AppCompat.ActionBar" /> in AppBarLayout so that we are getting black title.
  4. Apply <item name="android:windowLightStatusBar">true</item> in Theme.MyApplication so that we are getting black status bar icon.
  5. Apply the following code in MainActivity's onCreate (Before super).
Window w = getWindow();
w.setFlags(WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS, WindowManager.LayoutParams.FLAG_LAYOUT_NO_LIMITS);

Generate 1242 x 2208 screenshot for App Store

  1. Use iPhone 8 Plus simulator to generate 1242 x 2208 raw screenshot.
  2. Use https://www.appstorescreenshot.com/

Generate 1284 x 2778 screenshot for App Store

  1. Use iPhone 11 Pro Max simulator to generate 1242 x 2688 raw screenshot. (The reason we are using the iPhone 11 family is that at https://screenshots.pro, only the iPhone 11 has a minimalist design.)
  2. Use https://screenshots.pro/

Or, a better way is to login with Google account. Then, use the old template

https://screenshots.pro/editor?template_id=67d0b0ae-c2b9-40a6-9e90-3ed8b7af614f

Position X : 56.41658961175087
Position Y : 359.3928890266867
Width : 1173.1307603212942
Height : 2416.440725382908

Find error in iOS string resource file

plutil -lint Localizable.strings

Link to rate iOS WeNote app

https://apps.apple.com/app/id1562256136?action=write-review

Using data from production iCloud

https://stackoverflow.com/a/40414108/72437

Print dependency tree

In Android Studio's terminal, type the following command

./gradlew app:dependencies
./gradlew jstockandroid:dependencies

Whether using "app" or "jstockandroid", is depending on the folder name found in the project.

Debug multi sync feature

// This is old format
//select * from notification where request->>'to' in (select token from google where email = 'yancheng.cheok@gmail.com') order by ts desc;

select * from notification where request->'message'->>'token' in (select token from google where email = 'yancheng.cheok@gmail.com') order by ts desc;

select email from google where token in (select request->'message'->>'token' from notification where id >= 3030128 AND id <= 3030157);

How to test on Android Auto Backup feature

  1. Upload app into phone via Android Studio.

  2. Write some text, attach some images, attach some voices.

  3. Execute the following code in Android Studio's terminal

    adb shell bmgr backupnow com.yocto.wenote

    You should able to observe backup progress log

  4. Uninstall the app from device.

  5. Upload app into phone via Android Studio. We should observe the old data is still there.

Emergency Action Plan when Digital Ocean Disk is Full

  1. Go to jstock_notification folder
  2. Clean up the /tmp folder in postgres_backup docker
  3. Truncate notification and notification_data table in postgres docker

iCloud Document

Monitor sync activities

brctl log -w --shorten | grep CloudDocs

Python

C:\yocto\sandbox>python -m virtualenv venv
C:\yocto\sandbox>venv\Scripts\activate.bat
(venv) C:\yocto\sandbox>pip install requests
(venv) C:\yocto\sandbox>python A.py

Cloud Storage

Differnt provider profiles

C:\Users\yccheok\.aws\credentials

List all files

aws s3api list-object-versions --bucket wenote-b
aws s3api list-object-versions --bucket wenote-b --profile space --endpoint-url https://fra1.digitaloceanspaces.com
aws s3api list-object-versions --bucket wenote-b --profile wasabi --endpoint-url https://s3.eu-central-1.wasabisys.com

Inspect individual file

aws s3api head-object --bucket wenote-b --key user-2/attachment/f995bdb4-691b-4c44-8a1f-dd348665da82.jpg
aws s3api head-object --bucket wenote-b --key user-2/attachment/f995bdb4-691b-4c44-8a1f-dd348665da82.jpg --profile space --endpoint-url https://fra1.digitaloceanspaces.com
aws s3api head-object --bucket wenote-b --key user-2/attachment/f995bdb4-691b-4c44-8a1f-dd348665da82.jpg --profile wasabi --endpoint-url https://s3.eu-central-1.wasabisys.com

Android Studio

Clear app data

adb shell pm clear com.yocto.wenote

Python

Run Python in virtual environment

python -m venv .
Scripts\activate.bat

Docker

Download Django to local

C:\yocto\snapweb>docker-compose run --rm -v %cd%/django:/app -w /app django django-admin.py startproject web .
(https://docs.docker.com/compose/django/#create-a-django-project)

Run Django manage script

C:\yocto\snapweb>docker-compose run --rm -v %cd%/django:/app -w /app django python /app/manage.py changepassword root
C:\yocto\snapweb>docker-compose run --rm -v %cd%/django:/app -w /app django python /app/manage.py startapp accounts
C:\yocto\snapweb>docker-compose run --rm -v %cd%/django:/app -w /app django python /app/manage.py makemigrations

Generate empty migration file

C:\yocto\jstock-insider>docker-compose run --rm -v %cd%/django:/app -w /app django python /app/manage.py makemigrations users --empty -n alter_ts_default_to_now

Enable/disable Hyper-V

bcdedit /set hypervisorlaunchtype off (Disable to run Android emulator)
bcdedit /set hypervisorlaunchtype auto (Enable to run Docker)

Use tools from Docker to process data in host machine

docker run --rm -v $(pwd):/app -w /app php:cli php hello.php (Linux)
docker run --rm -v %cd%:/app -w /app php:cli php hello.php (Windows)

docker run --rm -v $(pwd):/app -w /app composer/composer create-project --prefer-dist laravel/laravel html (Linux)
docker run --rm -v %cd%:/app -w /app composer/composer create-project --prefer-dist laravel/laravel html (Windows)

Remove all images from PowerShell

docker stop $(docker ps -a -q)
docker ps -a -q | % { docker rm $_ }
docker images -q | % { docker rmi $_ }
docker volume prune

Clean Git checkout from master and overwrite everything

git fetch --all; git reset --hard origin/master

Clean up docker log

truncate -s 0 /var/lib/docker/containers/*/*-json.log

Clean build on ONE images in case something went wrong

docker-compose up -d --force-recreate --no-deps --build flask

Clean build on ALL images in case something went wrong

docker-compose up -d --force-recreate --build

Clear redis cache

docker exec -it jstockiex_redis_1 redis-cli FLUSHALL

Remove postgres volume

docker-compose down --volumes (DANGEROUS!!!)
docker-compose up -d --force-recreate --build

Let Flask access local drive

docker-compose.xml

  nginx:
    ...
    ports:
      - "80:80"
    ...

  flask:
    ...
    #
    # FOR DEVELOPMENT
    #
    volumes:
        - ./flask/:/app
    ...

flask/Dockerfile

    CMD /usr/local/bin/gunicorn --workers=5 main:app -b 0.0.0.0:5000 --error-logfile=/var/log/gunicorn3.err.log --reload

Get Python logging in Flask

Use the following code to perform printing in Flask: print("This is message", flush=True)
docker-compose logs -f

Postgres

Went into db container

docker-compose exec postgres sh

Login to localhost as user "postgres"

psql -h localhost -U postgres

List all databases

postgres-# \l

Use a database

postgres-# \c jstock_iex

List all tables

postgres-# \dt

Check whether news notifications are being sent today

select ts from notification where (request->'data'->'news_alerts') is not null order by ts desc limit 100;

Check user subscription

select * from google_subscription where (subscription_info->>'orderId') = 'GPA.3383-0878-7727-50427'; (expired)

select * from google_subscription where (subscription_info->>'orderId') = 'GPA.3359-8897-6679-16612'; (active)

Check table size usage

select table_name, pg_relation_size(quote_ident(table_name))
from information_schema.tables
where table_schema = 'public'
order by 2

Delete a row

delete from notification where ts < timestamp '2020-08-20 00:00:00';

Claim back disk space

vacuum full;

Restore from pgdump

(PGPASSWORD="$DB_PASSWORD" pg_dump -c -h "$DB_HOST" "$DB_DB" -p "$DB_PORT" -U "$DB_USER" > $FILE)
psql -h localhost -U postgres wenote_cloud_storage < /tmp/pg_dump-20210520_125646.sql

(PGPASSWORD="$DB_PASSWORD" pg_dump -c -C -h "$DB_HOST" "$DB_DB" -p "$DB_PORT" -U "$DB_USER" > $FILE)
psql -h localhost -U postgres < /tmp/pg_dump-20210520_131418.sql

RabbitMQ

Check queues

rabbitmqadmin -u <username> -p <password> list queues vhost name node messages message_stats.publish_details.rate

Facebook

Add debug key to Facebook

c:\yocto>keytool -exportcert -alias androiddebugkey -keystore c:\Users\yccheok\.android\debug.keystore | c:\openssl-0.9.8k_X64\bin\openssl.exe sha1 -binary | c:\openssl-0.9.8k_X64\bin\openssl.exe base64
Enter keystore password:  android

Google

Add debug key to Google

c:\yocto>keytool -exportcert -list -v -keystore c:\Users\yccheok\.android\debug.keystore
Enter keystore password:  android

Google Play store screenshots

Create an image 1242 x 2208
Scale down screenshot size to 90% till 972 x 1728
Place screenshot @ position x=135, y=345
Use font Tahoma 84 Fixed (96 DPI)

Google App Engine

gcloud app deploy --project jstock-webapp app.yaml

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Cheastsheet for programmer