[pull] master from donnemartin:master (#35)

* Add missing comma in Mint solution (donnemartin#399)

* Fix single point of failure typo (donnemartin#398)

* Fix layer 7 load balancers typo (donnemartin#317)

Co-authored-by: Alexander Teno <[email protected]>
Co-authored-by: panguncle <[email protected]>
Co-authored-by: shiyujiucsb <[email protected]>

README.md

@@ -665,7 +665,7 @@ Load balancers distribute incoming client requests to computing resources such a
 
 * Preventing requests from going to unhealthy servers
 * Preventing overloading resources
-* Helping eliminate single points of failure
+* Helping to eliminate a single point of failure
 
 Load balancers can be implemented with hardware (expensive) or with software such as HAProxy.
 
@@ -692,7 +692,7 @@ Layer 4 load balancers look at info at the [transport layer](#communication) to
 
 ### Layer 7 load balancing
 
-Layer 7 load balancers look at the [application layer](#communication) to decide how to distribute requests.  This can involve contents of the header, message, and cookies.  Layer 7 load balancers terminates network traffic, reads the message, makes a load-balancing decision, then opens a connection to the selected server.  For example, a layer 7 load balancer can direct video traffic to servers that host videos while directing more sensitive user billing traffic to security-hardened servers.
+Layer 7 load balancers look at the [application layer](#communication) to decide how to distribute requests.  This can involve contents of the header, message, and cookies.  Layer 7 load balancers terminate network traffic, reads the message, makes a load-balancing decision, then opens a connection to the selected server.  For example, a layer 7 load balancer can direct video traffic to servers that host videos while directing more sensitive user billing traffic to security-hardened servers.
 
 At the cost of flexibility, layer 4 load balancing requires less time and computing resources than Layer 7, although the performance impact can be minimal on modern commodity hardware.
 
@@ -710,7 +710,7 @@ Load balancers can also help with horizontal scaling, improving performance and
 ### Disadvantage(s): load balancer
 
 * The load balancer can become a performance bottleneck if it does not have enough resources or if it is not configured properly.
-* Introducing a load balancer to help eliminate single points of failure results in increased complexity.
+* Introducing a load balancer to help eliminate a single point of failure results in increased complexity.
 * A single load balancer is a single point of failure, configuring multiple load balancers further increases complexity.
 
 ### Source(s) and further reading

solutions/system_design/mint/README.md

@@ -242,7 +242,7 @@ class Budget(object):
     def create_budget_template(self):
         return {
             'DefaultCategories.HOUSING': income * .4,
-            'DefaultCategories.FOOD': income * .2
+            'DefaultCategories.FOOD': income * .2,
             'DefaultCategories.GAS': income * .1,
             'DefaultCategories.SHOPPING': income * .2
             ...